This invention relates to metal-insulator-semiconductor devices.
At the present time, GaAs device technology has been limited to two terminal luminescent (e.g., laser diode) and microwave (e.g., mixer and IMPATT diode) devices and Schottky gate field effect transistors (FETs). Depletion mode FETs that use anodic oxidation or silicon oxynitride for the gate insulation have been reported. The electrical properties of these anodic and pyrolitic dielectrics were investigated by Zeisse et al, Journal of Vacuumm Science Technology, Volume 14, page 957 (1977), who found that both dielectrics exhibit a significant amount of dispersion and hysteresis in capacitance-voltage (C-V) measurements. These properties, which are caused by interface states between the dielectric and semiconductor, are a problem in MOS and MIS FETs because dispersion increases noise and reduces gain, whereas hysteresis causes the operating point to be a function of previously applied signals.